Improvement in wood-grinders



Uivrrnn STATES A'rnN'r BENJAMIN F. BARKER, OF (JURTISVILLE,MASSACHUSETTS.

IMPROVEMENT lN WOODGRINDERS.

Specification forming part of Letters Patent No. 50,932, dated May i9,1h74; application led September 4, 1873.

To all whom it may concern:

Be it known that I, BENJAMIN F. BAKKER, of Ourtisville, Berkshirecounty, Massachusetts, have invented certain Improvements relating toMachines for Grinding Wood for PaperStock, of which the following is aspecification I have, in a patent issued to me, dated September 19,1871, No. 119,107, described a machine in which a stone revolving likethe upper stone of a grist-mill acts, by its periphery, upon masses ofwood contained in holders, which present awedge-form space for the wood,and in which the wood is continually urged toward the narrow end of thewedge by the pull ofthe stone. My present invention relates to the samegeneral construction; and consists in improvements in the holder,whereby the broad flange extending out from the' lower edge of thestone, and turning with it in my former method, is dispensed with, andthe action of the stone on the wood, as also the reverse action of thewood on the stone, is materially improved.

The accompanying drawings form a part of this specification, andrepresent my improved wood-holder and the adjacent parts.

Figure 1 is an elevation of the wood-holder detached from the machine,and viewed on the side which is presented to the stone when in use. Fig.2 is a plan view of the same filled with wood. This view also exhibits aportion of the stone and of the fixed casing which surrounds the stone.It also shows a screw, by which the distance of that end of the holderfrom the stone is adjusted at will. Fig. 3 is a transverse section onthe line S S in Fig. 1.

Similar letters of reference indicate like parts in all the figureswhere they occur.

C is the stone, rapidly and steadily revolved by some suitable power notrepresented; and Eis a xed casing, which surrounds it at a suitabledistance, as represented. The body of the wood-holder is composed of abottom, D, with sides H. It is made of cast iron, or other suitablerigid material, and is pivoted, near one end, on an arm, E', whichextendsinward from the casin g E, while the other end is held close tothe periphery of the` stone C by means of the screw G, and is adjustedinward thereby to compensate for the gradual reduccondition is plainlyindicated in Fig. 1. It is also inclined -in the direction of the radiusof the stone, so that any given point in the surface of the wood whichis presented to the stone moves downward a little on the stone as thewood moves forward in being consumed. I is a hand-lever, pivoted in anarm, H', projecting backward from the bottom of the wood-holder, andoperating a branch piece, B, carrying two horizontal rods, b b, attachedto a plate, M. Surrounding each of the rods b is a coiled spring, m, thetension of which urges the plate M forward, pressing forward any woodwhich may be before it, so as to force it into the narrow part of thewedge-like interior of the woodholder.

In operating the machine the periphery of the stone having been properlytrued and pecked, and the holder iilled with pieces of popA lar or othersuitable wood of a proper length, standing upright side by side, thetension of the springs m contributes its force, with the draft or pullof the stone, to urge the several pieces of wood constantly toward thenarrow end ofthe wedgelspace in which they are conncd. As the stoneremoves the successive increments from their inner faces, and they become narrower, they thus move forward in obedience to this force, andthe springs m extend, and maintain anearly-uniform tension thereon. Whenthis action has proceeded to a certain extent,the attendant introducesone or more fresh pieces of wood in a corresponding upright positionbehind the others, by taking them successively in one hand, and drawingback the plate M by acting on the hand-leverI with the other. Onliberating the hand-lever I, the force of the springs on is again feltto drive for ward the plate -M, and thus to urge forward the wood untilthe whole is consumed.

In order to make the tension of the springs m as nearly uniform aspossible, I employ stout wiresof spring brass or steel, coiled, each,`ina' large heliX, and nearly lill the interior of the helix by a loosesleeve that is free to roll.

Springs thus mounted maintaina proper tension, even when the plate M isin its eXtreme forward position, and, when drawn back by the hand-lever,remain in place without serious crookin g or other derangemen t.

There may be four or other desired number of these Wood-holders aroundeach stone C. There may, also, becorresponding wood-hold ers on theupper surface of the stone. Such might also be worked with some successon the lower surface, proper provisions being made in cach case forsupplying clear water, and for conducting away the water with thewood-pulp which it contains. l

The inclination of the motion of the wood,

- relatively to the stone, causes all ridges on the stone to be rapidlyworn off'. Suppose a series of ridges, parallel to each other, extendingaround the stone: They will tend to grind corresponding ridges in thewood 5 and then, as the fibers are ground off', they are necessarilyshort. But the base of each of' my wood-holders is so inclined that, asthe wood feeds slowly face of the stone works against `a true surface oneach piece of' wood, and long bers are ground oft', which may, intheory, extend the whole height of the stone. In practice I get, bymeans of my improvement, much longer fibers than heretofore, and thisstill further improves the resulting pulp.

I claim as my invention- 1. In combination with a revolving stone, C,the wood-holder described, having its bottom D inclined relatively tothe stone, so that the wood, in feeding forward, shall move oblique] yacross the line of motion of' the grinding-surface, as specified.

2. The grindingstone C, and the woodholder H, in combination with thefollower M, springs m, and lever I, and its connecting branch piece B,with its rods b b, for conven iently drawing back the follower for theintroduction of new material, as herein specified.

In testimony whereof I have hereunto set my hand this 28th dayof August,1873, in the presence of two subscribing witnesses.

BENJA. F. BAKKER.

Witnesses A. B. PITKIN, K. E. GARDNER.

